Thiocarbonate describes a family of

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s with the general

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

(''x'' = 0, 1, or 2): *for ''x'' = 2 it is monothiocarbonate ion *for ''x'' = 1 it is dithiocarbonate ion *for ''x'' = 0 it is trithiocarbonate ion Like the

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

dianion, the thiocarbonate ions are trigonal planar, with carbon atom at the center of triangle, and oxygen and sulfur atoms at the peaks of the triangle. The average bond order between C and S or O is . The state of protonation is usually not specified. These anions are good nucleophiles and good

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

s. Thiocarbonates are salts of those ions as well (e.g. sodium dithiocarbonate ). Thiocarbonates are esters of thiose ions as well. They contain trigonal planar divalent

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...

s similar to these anions.

Monothiocarbonate

Monothiocarbonate is the dianion , which has C_2v symmetry. Monothiocarbonate arises by the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

of thiophosgene or the reaction of base with

carbonyl sulfide Carbonyl sulfide is the chemical compound with the linear formula OCS. It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom. Carbonyl sulfide can be consi ...

: : The esters of monothiocarbonic acids are called monothiocarbonates as well (e.g. ''O''-ethyl-''S''-methyl monothiocarbonate ).

Dithiocarbonates

Dithiocarbonate is the dianion , which has C_2v symmetry. It arises from the reaction of aqueous base with

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical n ...

: : Important derivatives of dithiocarbonates are the

xanthate 150px, Sodium salt of ethyl xanthate Xanthate usually refers to a salt with the formula (R = alkyl; M+ = Na+, K+), thus they are the metal-thioate/''O''-esters of dithiocarbonate. The name ''xanthates'' is derived from Ancient Greek ''xanthos' ...

s (''O''-esters of dithiocarbonates), with the formula . These salts are typically prepared by the reaction of sodium alkoxides with carbon disulfide. Another group of dithiocarbonates have the formula . They are often derived by hydrolysis of the corresponding trithiocarbonates (RS)₂CS. One example is tetrathiapentalenedione, a

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

that consists of two dithiocarbonate groups.

Trithiocarbonates

Trithiocarbonate is the dianion , which has D_3h symmetry. Trithiocarbonate is prepaared by the reaction of hydrosulfide () with carbon disulfide: : The relatively elusive trithiocarbonic acid has been characterized by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

. Dimethyl trithiocarbonate, , is an ester of trithiocarbonic acid.

Perthiocarbonates

Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion , which contains one sulfur–sulfur bond. Perthiocarbonic acid (or tetrathioperoxycarbonic acid / disulfanylmethanedithioic acid / CAS#13074-70-9) has never been obtained in pure form.A Text-book of Inorganic Chemistry, Volume 7, Issue 2, 1931, p. 269
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References

{{Reflist Carbonates Oxyanions Sulfur ions